Telephone-exchange system



TELEPHONE EXCHANGE SYSTEM Filed Dec. 31, 1921 change systems and more particularly to PatentedJan. 12, 1926, i

.UNITEDYSTATES TRIC COMPANY, INCORPORATED, CF 1 IEW,YORK, N. TYL, A CORPORATION OF NEW YORK.

1 TELEPHONE-EXCHANGE sYsriiivi.

Application filed December 31, 1921. Serial No. 52 ,226.

.To all whom it may concern:

Be it known that I, EUGENE HiiLwIo, a citizen of the United States, residing at Hackensack, in the county of Bergen, State of New Jersey, have invented certain new and useful Improvements in Telephone- Exchange Systems, of which the following is a full, clear, concise, and exact description. r

This invention relates to telephone exsuch systemsin which connections between telephone lines terminating at manual and automatic exchanges are. established by an operator by way of cord and trunk circuits over which automatic switches are controlled by the operator for effecting connections between the lines terminating at the manual and automatic exchanges.

One object of the invention is to simplify and improve systems of this character which employ a full metallic dialing circuit for controlling the automatic switches.

A further object. of the invention'is to control the character of a trunk circuit and the association of the supervisory bridges therewith by changing the direction of current flow over a conductor associated with the trunk circuit.

To carry out the objects of the invention a key only is provided in each cord circuit for rendering the sender individual to a cord circuit. The trunk circuit extending from the operators pos tion to the automatic exchange is provided with means which normally prevent or block the flow ,of direct current, from the manual to the automatic exchange or vice versa, when the cord circuit is connected to the trunk circuit. A pair of bridges, one foreach side of the blocking means, is provided in the trunk circuit for controlling the supervisory apparatus in the cord circuit; The insertion of a plug of the cord circuit into a jack of the trunk circuit closes a sleeve circuit over which the connection of the bridges across the trunk circuit is controlled. An actuation of the key then reverses the flow of current over the sleeve circuit causing the short circuiting of the blocking means and the connection of the sender across the talkseassi .i

mm mart; f.

EUGENE C. HELlVIG, OE HACK'ENSACK, NEW JERSEY, ASSIGNOR 'I'O WESTERN ELEC- ing conductors of the trunk circuit thereby establishing the through dialing circuit.

By providing this reversal of 'curreiit when the key is actuated, the bridges are. held again reverses the flowlot current inf the.

-55, disconnected, the blocking means are short i sleeve causing the connection ofthe bridges.

to the trunk circuit and the removal of the short circuit from the blocking means. The

bridges now function when the called party answers. and hangs up, to actuate a supervisory signal at the QPGIZt-tOI S position.

Fora more complete understanding bi":

this invention reference may-be had to the following description and to the accompanying drawing which illustrates one embodiment of the invention.

There is shown in the drawing a tele-' phone line A which terminates at the man-f ual exchange where it may be connected with a cord circuit B in'any suitable and well known manner. The calling end otthe cord circuit '13 may be connected with a trunk circuit C extending from the manual to the automatic exchange, at which are provided the usual selector and connector switches for effecting connection between the I trunk circuit and the telephone lines. "A

connector switch is schematically indicated at K. It will be understood, however, that any desired number of selector switches may be connected between the trunk circuit C and the connector switch K. The apparatus shown to the left of the dotted line 1 .is

located at the manual exchange and to the right thereof at theiautomatic exchange. i

The subscriber at telephone line A having operator actuates listening key 5, connecting the operators telephone set inthe'circuit so that the operator may converse with the a calling subscriber to ascertain the number of the line with which connection is des red. Assuming that connection is desired with telephone line D, which terminates at the I outer left-hand alternate contacts.

automatic exchange, the operator inserts calling plug 6 of the cord circuit B into ack '7 of the trunk circuit C. Calling supervisory lamp 8 and sleeve relay 9 are thereupon operated a over a circuit extending from grounded battery lamp 8, resistance 43, sleeves of plug 6' and jack 7, inner left-hand normal contactsof relay 12, and winding of relay 9 to. groiuid.

The operator may now actuate the dial ing key 41 for the purpose of connecting the sender or dial S to the cord circuit, whereupon relays 11, 12, 13 and 14 are successively energized. Relay 11 is operated over a path extending asfollows: ground, normal contacts of polarized relay 19, right normal contacts oi irelay 13, winding of relay 11, lower winding of'coil 10, right-hand normal contacts of relay 12, tips'of jack 7 and plug 6, upper alternate contacts of key 41, contacts44 of dial S, winding of polarized relay 45, contacts 46 of key 41, rings of plug.,6 and jack 7 upper winding of coil 10, and left-hand normal contacts of relay l3 to grounded battery. Relay 11, in oper ating, completes a circuit for relay 12 over a path as follows: rounded battery, winding ofrelay'12, contacts 01"- rclay 11, sleeves of jack 7" and plug 6, lowermost contacts of L key 41 and resistance 42 to ground. Relay 12, in operating, looks through its inner left-hand: alternate contacts and through resistance 42 under control of the key 41. Lamp 8 which was lighted over a circuit including normal contacts of relay 12 remains lighted over a circuit including resist-- ance 42, when the key 41 is actuated. The

resistance. values-0f relays 12 and 9 and resistances 42 and 43 are so chosen that the sleeve; resistance during the time key 41 is actuated (or during the dialing period) is practically. the'same as when the key 41is in'normal position so that a substantially uniform busy test is, 'iven to the operator,

regardless ofthe position of the dialing key. The operation otrelay 12' renders the talkmg conductors of the trunk circuit C conductively continuous, ,,by short circuiting the condenser 22 by a direct current path trunk C, through the upper winding ofcoil 10, outer and inner left-hand alternate contacts of relay 13, lower windlng of coil 10, inner r1ght-hand normal contacts ot relay 12 to the tip talking conductor of the inner section of trunk C. This bridge, being open at the contacts of relay 12, performs no function at the present time. Relay 13, in operating, also completes a circuit for slow-to-release'relay 14 over a path extending from ground, normal contacts of polarizer relay 19, right-hand alternate.

contacts of relay 13, and windingof relay 14 to grounded battery. For thepurpose of indicating that relay 14 is of the slow-to release type, an arrow pointed in the direc: tion in whichthe armature is slowly moved, is shown. Relay 14, in operating, prepares a bridge for the outer section of the trunk circuit C, said bridge extending from the ring conductor of the outer section of trunk C, outer left-hand normal contacts otrelay. 12, outer contacts of relay 14, wind ng of.

ing from the operators position over the.

connected cord and trunk circuit to the automatic exchange. (not shown) may then be actuated to extend the connection to a connector. switch, such as K, whereupon impulse responsive relay ot the connector K will be energized over a path extending from ground, left-hand winding of relay 25, left-hand normal contacts of relay 26, outer left-hand alternate contacts of relay 12, ring contacts of jack? and plug6, contacts 46 .of key 41, winding of polarized relay 45, contacts 44 ofdials upper alternate contacts ofkey 41, tip con;

tacts or plug 6 and jack 7, inner right-hand alternate contacts ofrelay 12, inner normal contacts of relay 26, and right-hand winding of relay 25. to grounded battery.

As soon as the dial is. moved oil normal the contacts are closed and remain closed until the dial returns to normal position. The closure of contacts 60 short circuits relay 45 so as to reduce the resistance of the dialing path; The operator. by actuating the dial S may. set the switch K on the line D of the desired subscriber after which the bell at the station of line D maybe actuated in the well known. manner. The subscriber of station 1) in. removing the receiver from the switchhook causes the energization of relay 26. Relay 26 in operating reverses the battery connections to the talking con ductors of the trunk circuitwhereby the polarized relay 45 which isbridged. across the conductors of the cord circuit B is energized and closes its contact. this contact causes the energization of relay 49, which is common to an operators posisoon as the A non numerical switch The closing of llli] tion, over an obvious circuit. Relay 49 in operating causes a tone to be-transmitted to the operators telephone set'over a path.

extending from grounded .battery, interrupter 50, inner alternate contacts of relay 49, winding 52 of coil 55 and thence in parallel, one path extending through winding 54 and the other path extending through Winding 53 of coil 55 ,and receiver 51 through the outer alternate contacts of relay 49 to grounc. This tone is forthe-purpose of audiblyinforming the operator that shehas failed to restore the dialing key. Upon hearing such tone the operator will immediately restore dialing key 41 to normal. It will thus be seen that if the operator answers a second call at her position and fails to restore the dialing key utilized in completing aprecedingcall, she will receive an audible signal as soon as the called statlon of the preceding connection answers.

The operation will now be described in the case where the operator restores the dialing key 41 to'normal as soon as the dialing operation is complete. 'The restoration of key 41 to normal opens the locking circuit for relay 12 whereupon it releases.

paths around the condensers 22 and 23 so that the inner and outer sections of the trunk circuit for this current are conductively separated and opens the circuit for relay 13, which releases andcloses the original energizing circuit for relay 9, which operates. The restoration of key v41 to normal has therefore again reversed the flow of current over the sleeve circuit. being of the slow-to-release type does not retract its armature when relay 13 deenergizes because a substitute circuit to ground through-the contacts of relay 9 is provided and it thus-holds the bridge across the outer section of the trunk circuit when the dial key is restored to normal. Supervisory lamp 8 remains lighted over the circuit previously traced. As soon as the called station answers, polarized relay 19 operates over a circuit extending from grounded battery, right hand winding of relay 25,

outer left-hand alternate contacts of relay 26, ring of trunk C, outer left normal contacts of relay 12, outer contacts of relay 14, winding of polarized relay 19, coil 18, tip of trunk C, inner alternate contacts of relay 26, and left-hand winding of relay 25 to ground. Relay 19 in operating completes a circuit for relay 13 over a path extending from grounded battery, winding of relay 13 and contacts of relay 19 to ground. Relay 13 in operating connects the bridge, previously traced, across the inner section of the trunk circuit thereby causing the energization of relay 40 and the extinguishment of lamp 8 in the well known manner, to indicate to the operator that the'called party Relay 12 in releasing, opens'the direct current.

Relay 14 releasing opens the circuit/for relay 13,

which releases. Relay 13 in retracting its armatures opens the bridge across the inner section of thetrunk circuit causing the, deenergization or supervisory relay 40 and 1 the lighting of supervisory lamp 8 which nowserves as a disconnect signal to the op erator at, the manual oifice. Theoperator may thereupon disconnect the plug 6 from' the jack 7 whereupon all operated apparatus associated with the. calling end of the link circuit B and with the trunk circuit C i is released and restored to normal position.

- What IS claimed is:

1. In a telephone exchangesystem, plurality of subscribers lines, means including a cord circuit and a connected trunkcircuit for establishing a connection between two:

of said lines, an impulse sender for transmitting impulses over. the two sides of said trunk circuit 111. series, an inductive device in the trunk circuit, a keyi'or connecting said impulse sender to the cord circuit, a

relay, and means for energizing said relay during the actuation of said key'to provide a path around said inductive device.

2. Ina telephone exchange system, a plu rality of subscribers llnes, means including a cord circuit and. a connected trunk circiut for establishing a connection between two of said lines, an impulse sender for.

transmitting impulses over two sides ofsaid trunk circuit in series, an inductive device in the trunk circuit, a key for connecting said impulse sender to the cord circuit, a relay, and a circuit completed by the actuation of said key to energize said relay to provide a path around said inductive. device.

3. In a telephone exchange system, a plus 7 .rality of subscribers. lines, means including a trunk circuit and a connected cord circuit for'establishing a connection between two of said lines,-an impulse sender for transmitting impulses over thetwo sidesof the trunk circuit in series, condensers in the trunk circuit, a relay, and a key for controlling said relay to short circuit said con"- densers during the operation of said key.

4. In a telephone exchange system, a trunk circuit, a cord circuit, a supervisory signal in the cord circuit, condensers in the trunk circuit conductively dividing it into inner and outer sections, a bridge for the outersection, an impulse sender for the cord circuit, a key for connecting the sender in serial relationship with the talking conduckeyfor cstablishing'a direct currentpath' around the condensers, and uneans responsive to the restoration of the key for connecting said bridge to said trunk lcircuit toacontrol said signal.

5. In a telephone exchmige sys for the trunkcircuit for controlling said signal, a dial for sending impulses over two sides of the trunk circuitrinseries, a key in the cord circuit, and means responsive to the actuation of said key for short circuiting said condensers and i for connoc ting said dial to said -cord circuit.

6.111 a telephone exchange system, a

trunk circuit, condensersin said trunk circuit, acord circuit connected to thetrunk circuit, a signal in the cord circuit, a bridge for the trunk circuit for controlling said signal, a dial for sending impuises over two sides of the trunk circuit in series, a-key in the cord circuit, means responsive to the actuation of said key for short circuiting said condensers and for connecting said dial to said cord circuit, and means responsive to the restoration of said key for conrmcting said bridge to said trunk-circuit.

7. In a telephone exchange system, a

trunk circuit, condensers in said trunk cir cult, acord circuit connected to the trunk circuit, asignal in the cord circuit, a bridge for thetrunk circuit for controlling said signal, a dial for sending impulses over two sides of the trunkcircuit in series, a key in the cord circuit, means responsive to the actuation of said key for short circuitingsaid condensers and for connecting said dial to said cord circuit, and means responsive to the restoration of said key for: connecting said bridgeto said trunk circuit and for -removing saidshort circuits from said condensers.

8. In a telephone exchange system, a trunk circuit, condensers in said trunk-circuit, a cord circuit connected to the trunk 'CllCUlt, a signal in the cord circuit, a bridge for the trunk circuit for controlling said signal, a dial for sending impulses over-two sides of the trunkcircuit in series, a key in the cord circuit, and means controlled by said key over the sleeve of the cord and connected trunk circuit for controlling the short circuiting of said condensers.

9. In a telephone exchange system, a trunk circuit, condensers iirsaid trunk circuit, a cord circuitconnected to the trunk circuit, a signal in the cord circuit, a bridge for the trunk circuit for controlling; said signal, a dial for sending impulses over two sides ofthe trunk circuit in series, a key in the cordcircuit, and means controlled by team a trunk circuit,- condensers in saidtrun-k circuit, a cord circuit connected to the trunk: circuit, asignalin the cord circuit, abridge" saidkey. over the sleeve ofthecord and con nected ntrunik circuits. for; controlling the a shortxcircuiting 10f saiducondensers and for controlling the connection-of said bridge to said trunk: circuits i 10. Inca telephone system, a cord lOil'Cilit, a trunk circuit, a. dial for sending impulscs oversaid trunk circuit, assignal, abridgczassociated with the trunk for i controlling a said 1' signal, a key inthe cordfor.connecting the dial. *1 e ewith, means operative responsive to the interconnection of said cord and "trunk.

for causing),- said signal to "assume a certain condition nicans responsive 1 to the act u ationi of said ke; for changing the condition of said bridge, and meansopcratire responsive to th-er oration ofsaid key foi'acliangin'gi the-condition of said' signal. i

11.. In telephone exchange system, acord circuit, a trunk circuit, a talkingcircuit and trunk circuit, a source 0t: current included r in the control circuitga testcontact, means for reversing the. flow 0t icurrent :in the control circuit, and means for maintainingythe potential of the test 1 contact substantiaily; constant] i 13.. In a: telephone exchange: system, a: trunk circuit comprising apair otaitallcing conductors; a -.condenseri in each. oii g the talking conductors, a cord circuit nconnected Withutl ie trunk circuit, an impulsecsemler, a key for connecting the scnider'tothe cord circuit, a lGlElQFiIlfilllQ. trunkxcircuit operas! ing in: response to :the actuation ot the key for establishing direct current: path aroundeach oii the condensers, and -an ims pulse relay controllediby thesender ore-ria circuit including the. direct current paths around the condensers.

14. In a: telephone exchange system, a trunkacircuit comprising a p air of talking conductors, a. condenser in each; of" the talle ing i conductors, a1 cord circuit connected with thetrunk-circuit, an impulse sender, a key for connecting the. sender to the cord" circuit, a relayaiir the trunlr.circuit: operats ing-in response to the actuationwot the key for establishing a direct current path around each 'of 'the condensers, and means controlled by the. restoration ot the key' for: removing the direct current path around the condensers. r

15. In a telephone exchange'system, trunk conductors, a bridge, a third conductor, a source of current associated with said third conductor, means for reversing the direction of current flow over the conductor, and means responsive to the reversed current flow to control the association of the bridge with the trunk conductors.

16. In a telephoneexchange system, inductively continuous trunk conductors, a third conductor, a source of current associ ated therewith, means for reversing the direction of fiow of current over said third conductor from the source, and means responsive to the flowot current in the re versed direction for rendering the trunk conductors conductively continuous.

17. In a telephone exchange system, a,

trunk circuit, inner and outer sections therefor, a plurality of bridges, means interconnecting the sections, a conductor, a source oi current connected thereto, means responsive to a flow of current over the conductor from the source to change the character of the means interconnecting the sections, means for changing the character of the current flowing over the conductor, means respon-e ductor to conductively interconnect the sec-v tions, transmitting impulses over the conductively interconnected sections to control the switches and transm1tt1ng current of a different character over the conductor 'to conductively separate the sections.

19. In a telephone exchange system, a trunk circuit comprising a, pair of talking conductors, an impulse relay connected to one end of said trunk circuit, a cord cir-- cuit connected to the other end of said trunk I circuit, condensers in said trunk circuit, an

impulse relay, an impulse sender associated with said cord circuit, a key, and means controlled by the actuation of said key for connecting said sender to said cord circuit and for short circuiting said condensers to connect said sender in series relationship with said relay. A

20. In a telephone exchange system, an inductively continuous trunk circuit, a cord circuit connected thereto, an impulse sender, a key only for connecting the sender to the cord circuit and for rendering said trunlr circuitconductively continuous, an impulse relay, and a series circuit including two sides of said trunk circuit and said sender" for controllingsaid relay.

21. In a telephone exchange system, a

trunk circuit comprising a pair of talking conductors, asource of direct current con- 7' nected thereto, a cord circuit connected to said trunk circuit, a source'of direct current connected thereto, condensers in said trunk circuit for separating said sources, an impulse sender on one side of said condensers, an impulse relay on the other side of said condensers, a key, andmeanscontrolled by the actuation of said key for connecting said sender to said trunk circuitxand for short circuiting said condensers to place said relay under control of said sender.

In witness whereof, I hereunto subscribe my name this 27th day of December A. D.,

EUGENE C. HELWIG. 

